Purpose :
Multiple sclerosis (MS) is an inflammatory immune-mediated demyelinating disease that frequently affects the central nervous system. Approximately 20% of patients have optic neuritis as the first manifestation of the disease. Its frequency, heterogeneity and absence of definitive treatment make it a therapeutic and diagnostic challenge for both the patient and the clinician. The authors main goal was to evalute retinal changes in MS patients and the potential role of optical coherence tomography (OCT) in both diagnosis and monitorization of this disease.

Methods :
Retrospective study of 133 eyes of 87 patients, 38 patients with MS (Group 1), 9 patients with isolated optic neuritis (Group 2) and 40 healthy patients (Group 3) from the Neurophthalmology Department of Centro Hospitalar de Lisboa Central from January 2013 to August 2015. Both Group 1 and 2 were subdivided in eyes with or without optic neuritis.Patients were characterized according to gender, age, years of follow-up, best corrected visual acuity, presence of other ocular disorders and episodes of optic neuritis. Patients with other ocular pathologies were excluded.OCT (OCT Spectralis, Heidelberg Engineering) of the macular region was done in all patients, followed by automatic segmentation of retinal layers. Scans were centered at the fovea and obtained at a radius of 3 to 6 mm from the central, superior, inferior, nasal and temporal sectors. Statistical tests were made to calculate statistically significant results between different groups.

Results :
Total retinal thickness and internal retinal layers thickness, particularly in the retinal nerve fibre, ganglion cell and inner plexiform layer, was reduced in a statistically significant value (p<0.05) when compared to the control group. Results differed in Group 1 and 2 and in eyes with or without optic neuritis. There was also a statistically significant sectorial difference.

Conclusions :
OCT can currently be considered an imaging biomarker of global CNS atrophy for both monitoring neuronal degeneration and assessing non-invasively effectiveness of therapies that reduce neuroaxonal loss. The authors question the existence of a subset of patients with MS primary macular pathology with a normal peripapillary retinal nerve fiber layer.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.